Excerpt
Nutrient management, including management of nitrogen (N) inputs, was a key part of the Green Revolution, which increased global agricultural production and helped feed the world in the latter half of the twentieth century. While N is often applied to increase yields, and is indeed essential to meet the increased production demand that inevitably follows population growth, an extensive number of studies from regions throughout the globe have reported negative impacts related to N losses to the environment (Smith et al. 2018; Follett and Walker 1989; Hey 2002; Hey et al. 2005; Greenhalch and Sauer 2003; Delgado and Follett 2010; Juergens-Gschwind 1989; Dubrovsky et al. 2010; Glebe 2006), particularly when N was applied at excessive rates, allowing much of the unused N to quickly escape agroecosystems via atmospheric, surface runoff, and/or leaching pathways. Among the negative effects reported by these studies were contributions to the development of hypoxic zones and algae blooms; direct and indirect losses of nitrous oxide (N2O), a greenhouse gas (GHG) that exacerbates a changing climate; nitrate (NO3−) leaching losses that can negatively impact groundwater and surface water quality; and other negative environmental impacts. There is widespread agreement in the scientific community that emissions of N2O are…
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